COMMUNITY FORUM

using one P- trap for two drains

I'm redoing my bathroom and I'm installing a seperate shower and tub. The shower and tub are located side by side with a drywall between the two. My question is: Becasue the the drain of the tub is within three feet of the shower drain, can I tie the drain pipe coming from the tub into the shower drain pipe before the shower's P-trap? THe tub and shower would share the same P-trap and vent line. I figure that there is enough volume of water from the tub to move the water in the shower P-trap, and the run is short enough so there won't be a loss of speed. Will this work out?

THanks

LonnythePlumber

04:14PM | 01/26/05

No you cannot continuous waste a tub drain into a 2" shower drain tailpiece before the trap. Certainly our codes don't allow it, nor do I know of any engineering positions that would like it(and they like goofy).

I don't understand your thinking about the volume and speed principles. Our concern is not to have one fixture wash up into another and to protect the trap seal.

You should use two P traps. You may be able to use one vent although it would be better to bring an 1 1/2" vent up separately and then tie in above the ceiling to the existing vent. Is your current vent also the vent for the toilet and or lavatory?

Thanks for your quick response. I'm glad to have your advise. I'll use a seperate trap. My thinking was that it is no different than a double sink using one s-trap. I guess I'm missing something in the theory. Why would it behave any differently than how a double sink drains into one trap?

Regarding the vent, yes it currently ties into the vent from the toilet. I was going to tie it into the same line that the shower uses which ties into the toilet line and then into the main stack.

LonnythePlumber

04:58PM | 01/26/05

We can tie two kitchen sinks bowls or two lavatories together before the trap if they are within 30" and are only 1 1/2" tubular size (smaller than pipe size). This is called a continuous waste. We often still have to use a baffle tee to keep the water coming up in the other bowl or lavatory.

I'm not quite picturing your drain set up. Are you saying that you now have a 2" drain tieing into your toilet drain line before the toilet ties into the vent? I think you're going to have to have another vent to protect your new fixture. Showers need to have a 2" drain if you don't already have one.

Regarding the venting, I originally had a shower only, and no tub in the bathroom off the master bedroom. I'm adding the seperate tub. The shower had a trap which lead to the waste drain that the toilet tied into. The shower had its own vent coming out of the drain pipe after the trap as it should. That vent tied into the main vent stack. The toilet has its own vent that ties into the main vent stack. So your saying that the new tub can not share the same vent line with the shower? Can't I tie the tub vent into the shower vent which leads into the main vent stack or should they have their own lines to the main stack? THanks for your help with this!!